Improvement in screw-propellers



E. 3. P0 RTER. Screw- Propellers.

P-atented Jan. '12, 1,875.

WHNE SSES 06M.

ATTORNEYS.

-U1\TITED STATES ELBERT B. PORTER,

PATENT OFFICE.

OF HAVANA, GUBA'.

IMPROVEMENT IN SCREW-PROPELLERS.

Specification forming part of Letters Patent No. 158,734, dated January 12, 1875; application filed October 31, 1874.

'To all whom it may concern Be it known that I, ELBER'I B. PORTER, of

' -Havana, in Cuba, have invented a new and propeller, which may be constructed at less cost, more -conveniently and cheaply repaired when broken or injured, and capable ofproducing a considerable increase of speed.

The invention consists of a screwspropeller with semi-elliptic or otherwise bent and twisted blades attached atone or both-ends of shaft,

and provided with interior and exterior auxiliary wings of sufficient size and twist.-

In the drawing, A represents the propeller-shaft, to which are attached, at oneor both ends, three or more curved and twisted blades, B. For lighter vessels it may be sufficient to attach one end of the screw-blades merely to the shaft, the other ends being rigidly connected, but for larger vessels and heavier workitwill be preferable to extend the shaft centrally to the rear end of the blades and bolt them firmly thereto. The twisted blades B may be curved in semi-elliptic, oval, or roundshape, as found most effective by experiment. They are furthermore provided with interior and exterior auxiliary wings or blades 0 of suitable, size, curve, and twist, which are firmly bolted undersuitable inclination near the middle and rear parts to the main blades, for the purpose of increasing the propelling surface without causing the dragging or vibrating of any parts.

The propeller is made of rolled-metal plates, each auxiliary and main blade being separately attached, so that any part may be repa-red without interfering with the other parts.

Having thus described my invention, I claim as new-and desire to secure' by Letters Patent A screw-propeller constructed of three or more curved and twistedblades attached at one or both ends to the shaft, and provided with projecting interior and exterior auxiliary blades or wings, substantially in the manner and for the purpose set forth.

ELBERT B. PORTER. Witnesses:

HENRY O. HALL, U. S. Consul- General, L. V. SCHMIDT, J. W. SANGER. 

